Printing is a process of depositing a substance onto the surface of a substance receiving substrate to produce graphic images (e.g., text and designs). A typical example of printing involves depositing ink on paper using a printing press. The development of print technologies has provided major progress in many areas on a large scale basis including the dissemination of information and the manufacture of goods relying on such technologies. Two print methods commonly used for depositing or printing graphic images onto the receiving substrate are lithographic printing and screen printing.
Lithographic printing utilizes printing plates having patterns formed from a series of grooves into which a thick ink is initially deposited with a suitable applicator. The grooves are configured for retaining a quantity of ink, while the areas adjacent to the grooves are rendered free of ink through careful wiping and scraping. The corresponding pattern is transferred after impressing the ink-loaded grooves onto the substrate surface with sufficient pressure whereby the surface contacts the ink retained in the grooves. This method of printing is relatively inexpensive and the resolution, density and quality of the printed image is generally adequate. However, when used on soft, elastomeric materials, the printed images are less satisfactory.
Screen printing is a print method suitable for use on a wide range of materials including textiles, ceramics, wood, paper, glass, metal and plastic. The method involves the use of a woven mesh or screen supported on a frame. An ink-blocking stencil is formed by blocking off parts of the screen in the negative image of the print. The open, unblocked parts representing the positive image of the print permit passage of the ink unto the substrate surface. The ink is pressed through the open areas of the screen to deposit a sharp-edged image onto the substrate surface below. A fill blade or squeegee is generally used to force ink into the mesh openings by moving it across the stencil screen to promote transfer through capillary action. Screen printing is more versatile than traditional printing techniques. The surface does not have to be printed under pressure and it does not have to be planar or flat. Screen printing also provides good color depth, enhanced definition and overall better quality images.
High-throughput commercial printing utilizes solvent-based inks to ensure rapid drying and good adhesion to the substrate surface. However, such inks suffer several drawbacks. Certain substrates, such as those composed of an elastomeric material, are not compatible with such solvent-based inks. These inks are formulated with solvents that usually penetrate the elastomeric material causing temporary physical changes such as swelling. Although the elastomeric material eventually returns to its original state as the solvent evaporates, its physical properties including barrier integrity may be adversely affected. In addition to the problem of incompatibility with elastomeric materials, solvent-based inks contain components that pose potentially harmful health effects on humans through contact with such inks printed on such elastomeric materials.
Accordingly, there is a need for a system for depositing an imprint onto a substrate, especially tubular or cylindrically-shaped substrates. There is also a need for a system for depositing an imprint onto a substrate with improved precision and accuracy.